Here is the obit of Pezda.
https://www.legacy.com/obituaries/de...&pid=182758852
It does not mention a grandson but does mention a nephew, then living in Greensboro, NC. (It is easy to find an address using anywho.com).
I looked back at the armyariforces.com forum (not longer in existence but bits and pieces are in the internet archives).
If you put your cursor on the title of the first item, regarding Pezda, you can see that a "Jack Pastor" was requesting information:
http://web.archive.org/web/201408021...h-FG-f343.aspx
On the Ancestry.com message boards, there is a request by Jack Pezda (aka Jack Pastor) from 2012 (who gives his email address) for information on the Pezda family in Detroit. Perhaps he was the one you were in contact with. I can pm you the email used he was using if you would like.